#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <math.h>
#include <string.h>

//https://www.nowcoder.com/practice/eb94f6a5b2ba49c6ac72d40b5ce95f50?tpId=37&&tqId=21233&rp=1&ru=/ta/huawei&qru=/ta/huawei/question-ranking

int cmpare(const void *A, const void *B) {
    return *(char *) A - *(char *) B;
}

int StatisticsChar(char *nums, int numsSize){
    int count = 0;
    if (numsSize > 0) {
        count++;
    }
    qsort(nums, numsSize, sizeof(char), cmpare);
    for (int i = 1; i < numsSize; i++) {
        if (nums[i - 1] != nums[i]) {
            count++;
        }
    }
    return count;
}

int main() {
    char str[1000];
    scanf("%s", str);
    printf("%d", StatisticsChar(str, strlen(str)));
    return 0;
}